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If you can go digital, stop watches run continuously.
On Jan 10, 2008, at 1:30 PM, Geoffrey Kolbe wrote:
>
> Thankyou for this Paul. I was hoping to get away from using
> essentially two
> clocks - a chronometer (WWV in your case) and what amounts to a
> deck watch
> (the stop watch).
>
> Stop watches usually have a maximum period over which they will run
> as a
> stop watch - usually about ten hours or so. So it is not possible
> to start
> a common stop watch at the top of the hour at midnight and let it
> run on
> for months more.
>
> Geoffrey Kolbe
>
>> Years ago when I computed satellite orbital elements from visual
>> observations, I obtained UTC from from a digital stopwatch. I
>> started at
>> a known time by listening to WWV on a radio. Rather than the top of a
>> minute, I started the watch on the 10th second of the minute. This
>> allowed me to catch the rhythm of the seconds ticks, and hit the
>> button
>> at the instant of the tick, rather than reacting to the tick. (WWV
>> omits
>> the ticks at the 29th and 59th seconds, which makes this method
>> harder
>> to use at the top or bottom of a minute.)
>>
>> After starting the watch, I would then test for an accurate
>> setting by
>> hitting the "split" button (to temporarily freeze the display
>> while the
>> watch continued to run) on several ticks, checking for a near zero
>> fractional seconds reading each time. With a bit of practice it's no
>> great trick to hit the mark plus or minus .02 second.
>>
>> To time satellite observations, I used the split button and let the
>> stopwatch memory save the times. It could hold up to 10, which was
>> more
>> than I ever needed.
>
>
> >
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